OPC / Proanthocyanidins
OPC / Proanthocyanidins is a unrated form of Grape Seed Extract, used in 289 on-market products .
Typical standardization: Standardized to OPC / proanthocyanidins; percentage varies by product (label examples cite 95%, "95% extract", procyanidolic value 95). Extracts declared by total polyphenols are not separable (bare "Polyphenols" is also an ordinary row name) and resolve to the unspecified form
Why this tier: Standard commercial specification; the BP/metabolic RCTs dosed 150-600 mg/day of extracts described as polyphenol/proanthocyanidin-rich and one 300 mg/day trial found no significant ambulatory BP effect, but no trial compared standardization levels at equal dose, so standardized vs unstandardized is not ranked.
Source: Sivaprakasapillai B et al. 2009, Metabolism 58(12):1743-1746, PMID 19608210; Ras RT et al. 2013, Br J Nutr 110(12):2234-2241, PMID 23702253; Zhang H et al. 2016, Medicine (Baltimore) 95(33):e4247, PMID 27537554